Two long and straight conductors are parallel to the z-axis. conductor 1 carries a current i-10 a in the +z direction and is located at (-15.0 cm, 0). conductor 2 carries a current of 15 a in the -z direction and is located at (-15.0 cm, +20.0 cm). (a) what are the coordinates of the point where the net magnetic field due to the two conductors is zero? (b) if a third long and straight conductor, parallel to the z-axis and carrying a current is 20 a (same direction as ii) is placed at the origin, find the magnitude and direction of the magnetic force per unit length on this conductor due to the first two.